According to MSNBC
the attack took place at Forward Operating Base Chapman in Khost province. There are no details of what carnage took place as of yet.
The base is home to US and other foreign forces.
MSNBC has been in contact with the NATO-led International Security Assistance Force. Spokeswoman Lieutenant Commander Katie Kendrick has confirmed the attack.
"There is ongoing activity there, but it is fresh and I can't give more details," Kendrick said.